#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <inttypes.h>
#include <sys/poll.h>
#include <sys/types.h>
#include <sys/stat.h>

#ifndef cpu_to_le32
#define cpu_to_le32(x) (x)
#endif

typedef uint8_t u8;
typedef uint32_t u32;

#define CRC32_POLY 0xe792105a
static inline u32 crc32_byte(u32 crc, const u8 data)
{
	unsigned int i;

	crc ^= data;
	for (i = 0; i < 8; i++) {
		u32 m = -(crc & 1) & CRC32_POLY;
		crc = (crc >> 1) ^ m;
	}
	return crc;
}

static inline u32 crc32_byte_poly(u32 crc, const u8 data, u32 poly)
{
	unsigned int i;

	crc ^= data;
	for (i = 0; i < 8; i++) {
		u32 m = -(crc & 1) & poly;
		crc = (crc >> 1) ^ m;
	}
	return crc;
}

#define GBOOT_POLY 0xd79025c9

static u32 gboot_crc32(u32 crc, const u8 *buf, unsigned int len)
{
	do {
		crc = crc32_byte_poly(crc, *buf++, GBOOT_POLY);
		len--;
	} while (len > 0);
	return crc;
}

void hwcode_write(const void *buf, unsigned int count)
{
	const unsigned char *ibuf = buf;
	unsigned char fbuf[2048];
	unsigned int i;

	if (count > 2048)
		abort();

	for (i = 0; i < count; i++) {
		fbuf[2 * i + 0] = 'h' + ((ibuf[i] >> 4) & 0xf);
		fbuf[2 * i + 1] = 'h' + ((ibuf[i] >> 0) & 0xf);
	}
	write(1, fbuf, 2 * count);
}

void usage(const char *name)
{
	fprintf(stderr, "usage: %s FILE\n", name ? name : "gboot-send");
}

int main(int argc, char *argv[])
{
	unsigned char buf[1024];
	unsigned char msg[3];
	struct pollfd pfd[1];
	unsigned int i;
	u32 crc = 1;
	int ret;
	const char *fname;
	int fd;

	if (argc < 1) {
		usage(argv[0]);
		exit(128);
	}
	fname = argv[1];
	if (!fname) {
		usage(argv[0]);
		exit(128);
	}

	fd = open(fname, O_RDONLY);
	if (fd == -1) {
		fprintf(stderr, "open(%s): %s\n", fname, strerror(errno));
		exit(128);
	}

	fprintf(stderr, "Press ENTER to continue...\n");
	pfd[0].fd = STDIN_FILENO;
	pfd[0].events = POLLIN;
	for (;;) {
		crc = crc32_byte(crc, 0);
		msg[0] = 0xff;
		msg[1] = 'H' + ((crc >> 4) & 0xf);
		msg[2] = 'H' + ((crc >> 0) & 0xf);
		write(1, msg, 3);
		i++;

		ret = poll(pfd, 1, 5);
		if (ret > 0 && (pfd[0].revents & POLLIN)) {
			ret = read(STDIN_FILENO, buf, 1);
			if (ret == 1 && (buf[0] == '\n' || buf[0] == '\r'))
				break;
		}
	}
	fprintf(stderr, "sync...\n");

	for (i = 0; i < 4000; i++) {
		crc = crc32_byte(crc, 0);
		msg[0] = 0xff;
		msg[1] = 'H' + ((crc >> 4) & 0xf);
		msg[2] = 'H' + ((crc >> 0) & 0xf);
		write(1, msg, 3);
		usleep(100);
		i++;
	}
	write(1, "=", 1);
	fprintf(stderr, "Sending code...\n");

	write(1, "=gboot:", 7);
	crc = 0;
	for (;;) {
		ret = read(fd, buf, sizeof(buf));
		if (ret < 0)
			break;
		if (!ret)
			break;

		hwcode_write(buf, ret);
		usleep(100);
		crc = gboot_crc32(crc, buf, ret);
	}
	crc = cpu_to_le32(crc);
	hwcode_write(&crc, 4);
	write(1, "\n", 1);
	return 0;
}